<?php

/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Validate
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Ccnum.php 16223 2009-06-21 20:04:53Z thomas $
 */


/**
 * @see Zend_Validate_Abstract
 */
require_once 'Zend/Validate/Abstract.php';


/**
 * @category   Zend
 * @package    Zend_Validate
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Validate_Ccnum extends Zend_Validate_Abstract
{
	/**
	 * Validation failure message key for when the value is not of valid length
	 */
	const LENGTH   = 'ccnumLength';

	/**
	 * Validation failure message key for when the value fails the mod-10 checksum
	 */
	const CHECKSUM = 'ccnumChecksum';

	/**
	 * Digits filter for input
	 *
	 * @var Zend_Filter_Digits
	 */
	protected static $_filter = null;

	/**
	 * Validation failure message template definitions
	 *
	 * @var array
	 */
	protected $_messageTemplates = array(
	self::LENGTH   => "'%value%' must contain between 13 and 19 digits",
	self::CHECKSUM => "Luhn algorithm (mod-10 checksum) failed on '%value%'"
	);

	/**
	 * Defined by Zend_Validate_Interface
	 *
	 * Returns true if and only if $value follows the Luhn algorithm (mod-10 checksum)
	 *
	 * @param  string $value
	 * @return boolean
	 */
	public function isValid($value)
	{
		$this->_setValue($value);

		if (null === self::$_filter) {
			/**
			 * @see Zend_Filter_Digits
			 */
			require_once 'Zend/Filter/Digits.php';
			self::$_filter = new Zend_Filter_Digits();
		}

		$valueFiltered = self::$_filter->filter($value);

		$length = strlen($valueFiltered);

		if ($length < 13 || $length > 19) {
			$this->_error(self::LENGTH);
			return false;
		}

		$sum    = 0;
		$weight = 2;

		for ($i = $length - 2; $i >= 0; $i--) {
			$digit = $weight * $valueFiltered[$i];
			$sum += floor($digit / 10) + $digit % 10;
			$weight = $weight % 2 + 1;
		}

		if ((10 - $sum % 10) % 10 != $valueFiltered[$length - 1]) {
			$this->_error(self::CHECKSUM, $valueFiltered);
			return false;
		}

		return true;
	}

}
